Collimator for filaments of high modules

ABSTRACT

Apparatus for arranging filaments having a modulus of elasticity in excess of 40 X 106 in a linear array wherein the filaments are parallel and uniformly spaced. The apparatus defines alternate grooves which are vertically and transversely offset from one another and which support the filaments over several inches of their length.

United States Patent 1191 Shulze Nov. 25, 1975 1 1 COLLIMATOR FOR FILAMENTS OF HIGH 3.277.537 10/1966 Rocder ct a1 242/157 R 3543.984 12/1970 Mansfield 226/196 MODULUS Charles E. Shulze, Glastonbury, Conn.

Inventor:

United Technologies Corporation, Hartford, Conn.

Filed; Oct. 25, 1974 Appl. No.: 518,033

Assignee:

Field of Search .y 226/196; 242/157 R;'

19/65 R. 65 T. 66 T. 150, 288; 57/106, 108

References Cited UNITED STATES PATENTS 5/1945 Nelson 2-12/157 R Primary E.vumil1erAllen N. Knowles Attorney, Agent, or Firm-Fishman & Van Kirk [57] ABSTRACT Apparatus for arranging filaments having a modulus of elasticity in excess of 40 X 10" in a linear array wherein the filaments are parallel and uniformly spaced. The apparatus defines alternate grooves which are vertically and transversely offset from one another and which support the filaments over several inches of their length.

10 Claims, 9 Drawing Figures US. Patent Nov. 25, 1975 Sheet 1 of2 3,921,882

US. Patent Nov. 25, 1975 Sheet20f2 3,921,882

COLLIMATOR FOR FILAMENTS OF HIGH MODULUS BACKGROUND OF THE INVENTION:

1. Field of the Invention The present invention relates to the manufacture of composite materials comprising parallelly oriented filaments embedded in a matrix. More specifically, this in vention is directed to collimators for filaments of high modulus. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art A composite material, as this term is now well known in the art, comprises a plurality of filaments embedded in a matrix material. The filaments will typically be comprised of a metallic material. Considering commercially available boron filaments for purposes of expla= nation, such filaments actually comprise a layer of amorphous boron which has been deposited on a tungsten wire substrate by a technique such as the known BCl H process disclosed in U.S. Pat. No. 3,549,424. Composite materials are customarily supplied to end users in tape form and are known to possess highly desir able physical characteristics. These desirable characteristics result from the fact that materials produced in fibrous or filament form frequently exhibit a higher elastic modulus and, accordingly, higher stiffness and strength than possessed by the corresponding materials in bulk form. The development of structural high modulus composites has, accordingly, received considerable attention in recent years.

A composite material in tape form comprises a plurality of continuous lengths of filaments of high modulus embedded in a matrix. In the composite the matrix material must be employed to hold the filaments together and to distribute the load between filaments whereby the composite tape will act as a unit rather than as merely a bundle of filaments. It is, accordingly, essential that the filaments be distributed parallel to each other with uniform and specified spacing between adjacent filaments in order to insure proper functioning of the matrix material and particularly to insure that there will be no voids between adjacent filaments; any such voids permitting movement of the filaments which would have a deleterious affect on the overall strength of the composite tape.

At the present time composite materials are produced employing either batch or continuous type processes. In the typical batch process, for example as disclosed in U.S. Pat. No. 3,606,667, a cylindrical drum or mandrel is employed. A layer of material, for example an aluminum foil, is first applied to the drum and thereafter a first end of a filament is attached to the foil through the use of a double faced adhesive tape. The single filament is then wound as a helix onto the surface of the drum. Lateral displacement of a filament guide or of the drum is employed to accomplish the desired spacing. If necessary, the filament can be adhesively bonded to the foil by applying a binder to the filament as it goes on the drum. When the winding process is completed a matrix material is applied to produce a product known as a mono-layer tape. Considering the example where the drum is first wrapped with an aluminum foil, the matrix material may be aluminum which is applied by plasma spraying. Batch-type processes of the type briefly described have the disadvantage of low production rate because of the time employed to produce each relatively short length ofcomposite tape. Additionally, such batch type processes are characterized by difficulty in controlling the spacing between turns of the helix as the filament is wound on the drum. The difficulty in controlling spacing is, in part, attributable to the inherent stiffness of the filaments.

There have also been efforts to produce mono-layer composite tapes in a continuous fashion. In a typical continuous process the filaments are precoated; i.e., a resinous matrix material is applied to the filaments before they are gathered together to form a tape, the tape resulting from passing the coated filaments between pressure rolls. Such continuous processes attempt to achieve the desired parallelism and uniform spacing between filaments by controlling the thickness of the coating applied to the filaments prior to the application of pressure. However, since process parameters such as the viscosity of the resin cannot be controlled with the requisite accuracy, such continuous techniques inherently result in an undesirable variation in product quality.

A further prior art continuous" composite tape production method contemplates forcing a plurality of filaments into a flat array in a horizontal plane and thereafter applying a film of resin over the array. Parallelism and proper spacing of the filaments is attempted to be obtained by rolling the resin film to thereby force the matrix material between adjacent filaments. This further type of continuous" process has also been characterized by random spacing between filaments and thus undesirable variation in product quality.

It is to be noted that it has been proposed to borrow technology from the textile industry in an effort to partially collimate the filaments prior to embedding in the matrix material. As is well known, in the textile industry devices known as combs are employed in the orientation of fibers in a various weaving operations. However, there are no existing combs with sufficiently fine teeth to permit each high modulus filament of a material such as boron, the filaments having a nominal diameter in the range of 4-8 mils, to occupy its own space within the comb. Thus, efforts to employ special combs have resulted in the filaments being handled in bunches or groups and the resulting spacing was nonuniform. It is also to be noted that filaments of high modulus cannot accurately be guided by means of the single-point contact characteristic of a comb.

To summarize, in the manufacture of composite materials the filaments cannot be handled in the same manner as fibers in the textile industry because metallic filaments of high modulus lack the flexibility of natural and man-made fibers and will, in fact, break if caused to follow a path of sharp curvature. Additionally, there is no situation in the textile industry where similar problems of uniform spacing and maintenance of parallelism is encountered. Further, in the textile industry a matrix material which enters the spacing between individual fibers is not employed to hold the fibers together and to transfer a load between fibers as is the case with composite materials comprising high modulus filaments.

SUMMARY OF THE INVENTION The present invention overcomes the above briefly described and other deficiencies and disadvantages of the prior art by providing a novel collimator for filaments of high modulus. A collimator in accordance with the present invention is characterized by parallel grooves which receive and guide individual filaments over several inches of their length. Accordingly, as the high modulus filaments exit from the grooves, they project in the manner of cantilevered beams for laying purposes. Thus, when used for filaments of high modulus; i.e., filaments such as boron having a modulus of elasticity in excess of 40 X ID; the filaments will extend outwardly and will remain straight over an appreciable distance even though unsupported. If the filaments are captured within a reasonable but practical distance from the end of the collimator, such as by being laid onto the surface of a revolving drum, the requisite precision spacing will be maintained.

The present invention is further characterized by use of a plurality of grooved members to define the collimator. Because of the small diameter of the filaments, and the similarly close but uniform spacing desired, grooves for adjacent filaments in the composite being produced cannot be formed in the same surface of a collimator defining member. Accordingly, a plurality of vertically offset members are employed to define a collimator in accordance with the invention.

BRIEF DESCRIPTION OF THE DRAWING:

The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the several figures and in which:

FIG. 1 is a schematic representation of apparatus for use in a continuous composite tape manufacturing process, the apparatus of FIG. 1 employing a collimator in accordance with the present invention;

FIG. 2 is a top plan view of a collimator element in accordance with the present invention;

FIG. 3 is a partial cross-sectional side elevation view, taken along line 33 of FIG. 2, of the collimator element of FIG. 2;

FIG. 4 is a side elevation view of a collimator suitable for use in the apparatus depicted in FIG. 1;

FIG. 5 is a partial cross-sectional side elevation view, taken along line 5-5 of FIG. 4, of the collimator of FIG. 4;

FIG. 6 is a side elevation view of a second embodiment of a collimator suitable for use in the apparatus depicted in FIG. 1;

FIG. 7 is a partial cross-sectional side elevation view, taken along line 7--7 of FIG. 6, of the collimator of FIG. 6;

FIG. 8 is a side elevation view of a third embodiment of a collimator suitable for use with the apparatus depicted in FIG. 1; and

FIG. Q is a partial cross-sectional side elevation view, taken along line 9-9 of FIG. 8, of the collimator of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

With reference to FIG. 1, the application of the present invention to a continuous composite tape production line is depicted. A plurality of boron or Borsic filaments 10; Borsic filaments being boron filaments which have been provided with a silicon carbide diffusion barrier coating; are drawn from a creel or creels, not shown, and passed over leveling rolls 12 and 14. The filaments are thereafter directed through a filament gathering comb 16 to achieve approximate positioning thereof. After exiting from comb 16 the filaments are passed through a collimator, indicated generally at 18, which may be of the type disclosed in FIGS. 4-9. The spaced parallel filaments exiting collimator 18 are directed, through pressurized seals, into a vacuum press indicated generally at 20. Also directed into press 20 from respective supply reels are a pair of aluminum foils 22 and 22 and steel foils 24 and 24. The aluminum foils 22 and 22' function, in the end product, as the matrix material. The steel foils 24 and 24' are employed to prevent adherence of the aluminum to the heated plattens of press 20. In a manner well known in the art the filaments are embedded in the matrix material as a result of the application of heat and pressure within press 20. The composite tape and foils 24 and 24 are drawn from press 20 by pull rolls 26 and the steel foils 24 and 24' are rewound on storage reels for reuse. The composite tape 24 is similarly wound on a reel for storage and eventual use.

Referring now to FIGS. 4 and 5, a first embodiment of a collimator 18 for use in continuous process apparatus of the type shown in FIG. 1 or in batch-type processing apparatus is depicted. The collimator of FIGS. 4 and 5 comprises a pair of identical plates 30 and 32. Each of plates 30 and 32 contains a series of parallel grooves. Considering an example where 5.7 mil nominal diameter filaments are to be bound in the matrix material with a spacing of I40 filaments per inch, each of plates 30 and 32 will be grooved to a spacing of seventy per inch. When placed together and offset as shown, a precise spacing of filaments is achieved. It is to be noted that if an attempt was made to form all of the grooves in a single plate, again considering the example of the 5.7 mil nominal diameter filaments, and thus a nominal 6 mil groove diameter with a spacing of I40 filaments per inch, the spacing would be 1.1 mil. This spacing between grooves is too small for machining and the ridges left between adjacent grooves would have insufficient structural strength. The grooves formed in plates 30 and 32 must be at least as deep as the diameter of the filaments and will be characterized by sides which are at least partly parallel.

Further considering the example of 5.7 mil nominal diameter filaments, plates 30 and 32 are preferably 7 inches long and the distance from the exit end of collimator 18 to the point of tangency with the drum, in a batch-type process, or to the point of contact with the aluminum foil, in the continuous process of FIG. 1, will be approximately 6 inches.

The embodiment of FIGS. 6 and 7 differs from that of FIGS. 4 and 5 in that the grooves which properly orient the individual filaments are formed in opposite surfaces of a plate 34. Cover plates, such as plates 36 and 38, are secured to plate 34 in any suitable fashion in order to complete the collimator assembly.

In the embodiment of FIGS. 8 and 9 three plates, indicated at 40, 42 and 44, are employed. These plates may be spaced, as shown in FIG. 8, or may be sandwiched together. Each of the collimator elements will be provided with a cover plate if the spacing of FIG. 8 is utilized. If the collimator elements 40, 42 and 44 are sandwiched together, only the upper element 40 will be provided with a cover plate such as indicated at 46.

FIGS. 2 and 3 depict, respectively a top plan view and a cross-sectional side elevation view of a single plate or element of a collimator in accordance with the invention. In the embodiment of FIGS. 2 and 3 only five grooves are provided and it may clearly be seen from FIG. 2 that these grooves are parallel and extend the entire length of plate 52. If only a single grooved collimator plate 52 is employed a cover plate, not shown, will be employed therewith. Two of plates 52 may, of course, be arranged in the manner depicted in FIGS. 4 and 5 whereby l0 filaments may be simultaneously handled. In a batch-type process either the collimator or the drum will be caused to move whereby the filaments are laid down in the form of helices.

To summarize the novel features and advantages of the present invention, the disclosed collimator has been found to be superior to all prior art apparatus and proposed apparatus due to its ease of manufacture and because of its ability to achieve accurate filament positioning which results from the guiding of filaments of high modulus; i.e., filaments having a modulus of elasticity in excess of 40 X over several inches of their length. Since each filament is held in its own groove over a length of several inches, and due to the characteristics of boron and similar materials in filament form, the filaments which exit from the collimator may be characterized as cantilever beams. Thus, the filaments will extend substantially straight over an appreciable distance even though unsupported. Through the use of a plurality of grooved members, or the formation of the filament guiding grooves in opposite surfaces of a plate, sufficient wall thickness between grooves has been achieved to permit the collimator elements to be produced by comparatively inexpensive machining techniques.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Thus, by way of example, although fabrication of the collimator elements by means of milling grooves in plates or blocks has been discussed, the collimator elements can be produced by stacking pieces of shim stock with every second piece being raised to define grooves therebetween. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

1. Apparatus for arranging filaments having a modulus of elasticity in excess of 40 X 10 in a parallel spaced relationship comprising:

at least a first collimator member, said member defining at least a first planar surface with a first plurality of elongated parallel grooves therein, said grooves of said first plurality being at least as deep as the diameter of said filaments, said grooves of said first plurality being spaced by a distance in excess of the diameter of said filaments; and

means defining at least a second plurality of elongated parallel grooves, said grooves of said second plurality being equal in dimensions and spacing to said grooves of said first plurality, individual grooves of said second plurality being vertically and transversely offset from individual grooves of said first plurality, said first member and said means defining said second plurality of grooves 6 being arranged to deliver filaments passing through said grooves to spaced points along a common line.

2. The apparatus of claim 1 wherein said means defining a second plurality of grooves comprises:

a second collimator member, said second member defining at least a first planar surface with said second plurality of parallel grooves therein, said first planar surfaces of said first and second collimator members being arranged in an abutting facing relationship.

3. The apparatus of claim 1 wherein said means defining a second plurality of grooves comprises:

a plurality of grooves formed in a second planar surface of said first collimator member, said second surface being disposed oppositely to and parallel with said first surface; and wherein said apparatus further comprises:

means for retaining said filaments in said grooves of said first and second plurality.

4. The apparatus of claim 1 wherein said grooves of said first and second plurality receive and support individual filaments over a portion of their length exceeding three inches.

5. The apparatus of claim 2 wherein said grooves of said first and second plurality receive and support individual filaments over a portion of their length exceeding three inches.

6. The apparatus of claim 3 wherein said grooves of said first and second plurality receive and support individual filaments over a portion of their length exceeding three inches.

7. The apparatus of claim 1 wherein said means defining a second plurality of grooves comprises:

a second collimator member, said second member defining at least a first planar surface with said second plurality of parallel grooves therein.

8. The apparatus of claim 7 wherein said first surface of said second member is spaced from said first surface of said first member and wherein said apparatus further comprises:

means for retaining filaments in said grooves of said first and second plurality.

9. The apparatus of claim 8 wherein said retaining means comprises:

a cover plate affixed to said first planar surface of said second member; and

a second planar surface of said second member, said second surface of said second member being in abutting contact with said first surface of said first member.

10. A collimator for filaments having a modulus of elasticity in excess of 40 X 10 comprising at least two arrays of linear spaced parallel grooves, said grooves being alternately vertically and transversely offset from array to array, said grooves supporting the filaments over several inches of length, said arrays being positioned to deliver filaments passing through the collimator to spaced points along a common line with filaments exiting from the grooves of said first and second arrays being alternately disposed along said line. 

1. Apparatus for arranging filaments having a modulus of elasticity in excess of 40 X 106 in a parallel spaced relationship comprising: at least a first collimator member, said member defining at least a first planar surface with a first plurality of elongated parallel grooves therein, said grooves of said first plurality being at least as deep as the diameter of said filaments, said grooves of said first plurality being spaced by a distance in excess of the diameter of said filaments; and means defining at least a second plurality of elongated parallel grooves, said grooves of said second plurality being equal in dimensions and spacing to said grooves of said first plurality, individual grooves of said second plurality being vertically and transversely offset from individual grooves of said first plurality, said first member and said means defining said second plurality of grooves being arranged to deliver filaments passing through said grooves to spaced points along a common line.
 2. The apparatus of claim 1 wherein said means defining a second plurality of grooves comprises: a second collimator member, said second member defining at least a first planar surface with said second plurality of parallel grooves therein, said first planar surfaces of said first and second collimator members being arranged in an abutting facing relationship.
 3. The apparatus of claim 1 wherein said means defining a second plurality of grooves comprises: a plurality of grooves formed in a second planar surface of said first collimator member, said second surface being disposed oppositely to and parallel with said first surface; and wherein said apparatus further comprises: means for retaining said filaments in said grooves of said first and second plurality.
 4. The apparatus of claim 1 wherein said grooves of said first and second plurality receive and support individual filaments over a portion of their length exceeding three inches.
 5. The apparatus of claim 2 wherein said grooves of said first and second plurality receive and support individual filaments over a portion of their length exceeding three inches.
 6. The apparatus of claim 3 wherein said grooves of said first and second plurality receive and support individual filaments over a portion of their length exceeding three inches.
 7. The apparatus of claim 1 wherein said means defining a second plurality of grooves comprises: a second collimator member, said second member defining at least a first planar surface with said second plurality of parallel grooves therein.
 8. The apparatus of claim 7 wherein said first surface of said second member is spaced from said first surface of said first member and wherein said apparatus further comprises: means for retaining filaments in said grooves of said first and second plurality.
 9. The apparatus of claim 8 wherein said retaining means comprises: a cover plate affixed to said First planar surface of said second member; and a second planar surface of said second member, said second surface of said second member being in abutting contact with said first surface of said first member.
 10. A collimator for filaments having a modulus of elasticity in excess of 40 X 106 comprising at least two arrays of linear spaced parallel grooves, said grooves being alternately vertically and transversely offset from array to array, said grooves supporting the filaments over several inches of length, said arrays being positioned to deliver filaments passing through the collimator to spaced points along a common line with filaments exiting from the grooves of said first and second arrays being alternately disposed along said line. 